The present invention relates to apparatus for indicating the accumulated running time of engines. For example, an internal combustion engine for powering a tractor is ordinarily operated intermittently, and it is often desired for purposes of maintenance or of warranty validation to maintain an accurate indication of the cumulative amount of time that the engine has been operated since it was initially put into service. When a running time meter is intentionally disabled, it is difficult to estimate whether it was disabled recently or many running hours earlier. A need has been felt for a running time indicator that is difficult to disable accidentally or to disable intentionally in such a way as to give an appearance that the running time indicator became defective unintentionally, and for a running time indicator that is self-powered and which retains ts accumulated total despite a power interruption.